Cardiac ablation devices and methods

ABSTRACT

Devices and methods provide for ablation of cardiac tissue for treating cardiac arrhythmias such as atrial fibrillation. Although the devices and methods are often used to ablate epicardial tissue in the vicinity of at least one pulmonary vein, various embodiments may be used to ablate other cardiac tissues in other locations on a heart. Devices generally include at least one tissue contacting member for contacting epicardial tissue and securing the ablation device to the epicardial tissue, and at least one ablation member for ablating the tissue. Various embodiments include features, such as suction apertures, which enable the device to attach to the epicardial surface with sufficient strength to allow the tissue to be stabilized via the device. For example, some embodiments may be used to stabilize a beating heart to enable a beating heart ablation procedure. Many of the devices may be introduced into a patient via minimally invasive introducer devices and the like. Although devices and methods of the invention may be used to ablate epicardial tissue to treat atrial fibrillation, they may also be used in veterinary or research contexts, to treat various heart conditions other than atrial fibrillation and/or to ablate cardiac tissue other than the epicardium.

CROSS-REFERENCES TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 11/186,148 filed Jul. 20, 2005, now U.S. Pat. No. 7,591,818,which is a continuation-in-part of U.S. pat. application Ser. No.10/988,021, now U.S. Pat. No. 7,399,300, which was filed on Nov. 12,2004, which is a continuation-in-part application which claims priorityof U.S. patent application Ser. No. 10/410,618, now U.S. Pat. No.7,226,448, which was filed on Apr. 8, 2003, which is acontinuation-in-part of and claims priority of U.S. patent applicationSer. No. 10/272,446, now U.S. Pat. No. 6,849,075, which was filed Oct.15, 2002, which claims priority to U.S. Provisional Patent ApplicationSer. No. 60/337,070, filed Dec. 4, 2001, entitled “Methods and Devicesfor the Least Invasive Cardiac Surgery of Atrial Fibrillation.” U.S.patent application Ser. No. 10/988,021 also claims the priority to U.S.Provisional Patent Application Ser. No. 60/519,726, filed Nov. 12, 2003,entitled “Ablation Device.” The entire contents of these applicationsare hereby incorporated by reference.

BACKGROUND OF THE INVENTION

The present invention relates generally to medical devices and methods.More specifically, the invention relates to devices and methods forablating epicardial tissue to treat cardiac arrhythmias such as atrialfibrillation.

Atrial fibrillation (AF) is a heart beat rhythm disorder (or “cardiacarrhythmia”) in which the upper chambers of the heart known as the atriaquiver rapidly instead of beating in a steady rhythm. This rapidquivering reduces the heart's ability to properly function as a pump. AFis characterized by circular waves of electrical impulses that travelacross the atria in a continuous cycle. It is the most common clinicalheart arrhythmia, affecting more than two million people in the UnitedStates and some six million people worldwide.

Atrial fibrillation typically increases the risk of acquiring a numberof potentially deadly complications, including thrombo-embolic stroke,dilated cardiomyopathy and congestive heart failure. Quality of life isalso impaired by common AF symptoms such as palpitations, chest pain,dyspnea, fatigue and dizziness. People with AF have, on average, afive-fold increase in morbidity and a two-fold increase in mortalitycompared to people with normal sinus rhythm. One of every six strokes inthe U.S. (some 120,000 per year) occurs in patients with AF, and thecondition is responsible for one-third of all hospitalizations relatedto cardiac rhythm disturbances (over 360,000 per year), resulting inbillions of dollars in annual healthcare expenditures.

AF is the most common arrhythmia seen by physicians, and the prevalenceof AF is growing rapidly as the population ages. The likelihood ofdeveloping AF increases dramatically as people age; the disorder isfound in about 1% of the adult population as a whole, and in about 6% ofthose over age 60. By age 80, about 9% of people (one in 11) will haveAF. According to a recent statistical analysis, the prevalence of AF inthe U.S. will more than double by the year 2050, as the proportion ofelderly increases. A recent study called The Anticoagulation and RiskFactors in Atrial Fibrillation (ATRIA) study, published in the Spring of2001 in the Journal of the American Medical Association (JAMA), foundthat 2.3 million U.S. adults currently have AF and this number is likelyto increase over the next 50 years to more than 5.6 million, more thanhalf of whom will be age 80 or over.

As the prevalence of AF increases, so will the number of people whodevelop debilitating or life-threatening complications, such as stroke.According to Framingham Heart Study data, the stroke rate in AF patientsincreases from about 3% of those aged 50-59 to more than 7% of thoseaged 80 and over. AF is responsible for up to 35% of the strokes thatoccur in people older than age 85.

Efforts to prevent stroke in AF patients have so far focused primarilyon the use of anticoagulant and antiplatelet drugs, such as warfarin andaspirin. Long-term warfarin therapy is recommended for all AF patientswith one or more stroke risk factors, including all patients over age75. Studies have shown, however, that warfarin tends to beunder-prescribed for AF. Despite the fact that warfarin reduces strokerisk by 60% or more, only 40% of patients age 65-74 and 20% of patientsover age 80 take the medication, and probably fewer than half are on thecorrect dosage. Patient compliance with warfarin is problematic, and thedrug requires vigilant blood monitoring to reduce the risk of bleedingcomplications.

Electrophysiologists classify AF by the “three Ps”: paroxysmal,persistent, or permanent. Paroxysmal AF—characterized by sporadic,usually self-limiting episodes lasting less than 48 hours—is the mostamenable to treatment, while persistent or permanent AF is much moreresistant to known therapies. Researchers now know that AF is aself-perpetuating disease and that abnormal atrial rhythms tend toinitiate or trigger more abnormal rhythms. Thus, the more episodes apatient experiences and the longer the episodes last, the less chance ofconverting the heart to a persistent normal rhythm, regardless of thetreatment method.

AF is characterized by circular waves of electrical impulses that travelacross the atria in a continuous cycle, causing the upper chambers ofthe heart to quiver rapidly. At least six different locations in theatria have been identified where these waves can circulate, a findingthat paved the way for maze-type ablation therapies. More recently,researchers have identified the pulmonary veins as perhaps the mostcommon area where AF-triggering foci reside. Technologies designed toisolate the pulmonary veins or ablate specific pulmonary foci appear tobe very promising and are the focus of much of the current research incatheter-based ablation techniques.

Although cardiac ablation devices and methods are currently available,many advances may still be made to provide improved devices and methodsfor ablating-epicardial tissue to treat AF and other arrhythmias. Forexample, currently available devices can be difficult to position andsecure on epicardial tissue to perform an ablation. Devices such asbipolar ablation clamps and others can ablate tissue only in verylimited patterns, such as one or two straight lines. Ablation devicesoften have no means for shielding ablative energy, to avoid unwantedburning of tissues in the vicinity of the heart, such as the esophagus.Relatively few devices can be secured to epicardial tissue withsufficient force to allow for stabilization of the heart. And manyablation devices may not be introduced by minimally invasive means, thusrequiring an open surgical procedure. Typically, therefore, currentcardiac ablation procedures for AF treatment still require stopping theheart and using a cardiopulmonary bypass apparatus.

Therefore, a need exists for improved devices and methods for ablatingepicardial tissue to treat AF and other cardiac arrhythmias. Preferably,such devices and methods would provide ablation adjacent to and/orencircling one or more pulmonary veins, to disrupt conduction pathwaysand thus partially or completely treat AF. Also preferably, such devicesand methods would allow for minimally invasive ablation procedures, insome cases on a beating heart. Such devices might also provideadditional advantages, such as advantageous ablation patterns, shieldingof ablative energy and/or the like. At least some of these objectiveswill be met by the present invention.

BRIEF SUMMARY OF THE INVENTION

Devices and methods of the present invention provide for ablation ofcardiac tissue for treating cardiac arrhythmias such as atrialfibrillation. Although the devices and methods are often used to ablateepicardial tissue in the vicinity of at least one pulmonary vein,various embodiments may be used to ablate other cardiac tissues in otherlocations on a heart. Generally, devices of the invention include atissue contacting member for contacting a portion of the epicardialtissue of a heart and securing the ablation device to the epicardialtissue, and an ablation member for ablating at least a portion of thetissue. In various embodiments, the devices have features which enablethe device to attach to the epicardial surface with sufficient strengthto allow the tissue to be stabilized via the device. For example, someembodiments may be used to stabilize a beating heart to enable a beatingheart ablation procedure. Many of the devices may be introduced into apatient via minimally invasive incisions, introducer devices and thelike. Although much of the following description focuses on usingdevices and methods of the invention to treat atrial fibrillation (AF)by ablating epicardial tissue on a human heart, the devices and methodsmay be used in veterinary or research contexts, to treat various heartconditions other than atrial fibrillation and/or to ablate cardiactissue other than the epicardium.

In one aspect, a system for treating heart tissue to treat a cardiacarrhythmia comprises: at least one energy transmission member forapplying energy to the heart tissue in a pattern to treat the cardiacarrhythmia; at least one tissue securing member coupled with the atleast one energy transmission member for enhancing contact of the energytransmission member with the heart tissue; and at least one guidingmember coupled with at least one of the energy transmission member andthe tissue securing member for guiding the energy transmission memberand the tissue securing member to a location for treating the hearttissue.

Optionally, such as system may further include at least onevisualization member for enhancing visualization of the heart tissue andthe treatment location. In some embodiments, for example, thevisualization member may include an optic imaging device, a thermalimaging device, an ultrasound device, an electrical imaging device, aDoppler imaging device or the like, though any suitable device may beused. In some embodiments, an optic imaging device comprises a fiberoptic device positionable to view a posterior portion of the hearttissue. In other embodiments, a thermal imaging device measures at leastone heat transfer coefficient of the heart tissue to determine at leastone of a type and a thickness of the heart tissue. In still otherembodiments, an electrical imaging device measures electrical resistanceand/or impedance of the heart tissue to determine a type and/or athickness of the heart tissue.

In some embodiments, the at least one visualization member is removablycoupled with at least one of the at least one energy transmissionmember, the at least one tissue securing member and the at least oneguiding member. Also in some embodiments, the at least one visualizationmember may comprise at least one optic member for acquiring opticsignals of an area to be visualized, and wherein the visualizationmember includes at least one inflatable member coupled with thevisualization member at or near the optic member. For example, theinflatable member may provide a space in a body cavity and/or between atleast two body tissues to enhance operation of the optic member. In someembodiments, the inflatable member includes an inflation port in fluidcommunication with an inflation lumen coupled with the visualizationmember for allowing introduction of a liquid or a gas to inflate theinflatable member. In some embodiments, the inflatable member reducesmotion of the heart tissue when applied to the heart tissue.

Some embodiments of the invention also include at least one positioningdevice for contacting the heart tissue and positioning the heart tissuefor treatment. For example, the positioning device may comprise asuction positioning device. In some embodiments, the positioning devicereduces motion of a beating heart to further position the heart tissuefor treatment.

The energy applied to the heart tissue may be any suitable energy, suchas but not limited to radio frequency energy, ultrasound energy,microwave energy, cryogenic energy, thermoelectric energy and laserenergy. In some embodiments, optionally, the energy transmission membercontacts an epicardial surface of the heart tissue to transmit theenergy, and wherein the energy is transmitted from the epicardialsurface through the heart tissue to an endocardial surface. Sometimes,the energy is further transmitted through at least one of fat andconnective tissue covering at least part of the epicardial surface. Someembodiments also include at least one grounding device for dispersingthe energy from a patient undergoing an energy transmission heartprocedure. Some embodiments may also include at least one needle coupledwith the energy transmission member for insertion into the heart tissueto enhance the application of energy to the heart tissue. In some ofthese embodiments, the energy is transmitted from a tip of each needle.Optionally, the needle may be retractable. In some embodiments, forexample, the retractable needle is exposed and retracted via a pneumaticmember coupled with the energy transmission member. In some embodiments,the retractable needle is exposed and retracted automatically when theenergy transmission member contacts the heart tissue. Also in someembodiments, the depth of penetration of the retractable needle into theheart tissue is adjustable.

Some embodiments may also include at least one closed circuit feedbackloop for measuring and regulating operation of the energy transmissionmember. In some embodiments, either the energy transmission member orthe tissue securing member further comprises at least one fluid aperturefor applying fluid to the heart tissue to enhance the application ofenergy to the heart tissue.

In some embodiments, the energy transmission member is coupled with atleast one guiding member such that a change in shape of the guidingmember causes a corresponding change in shape of the energy transmissionmember. For example, the guiding member may comprise a deformable linearmember, its shape being adjustable by a user, and wherein the energytransmission member comprises a deformable linear member coaxiallycoupled with the guiding member so as to move with the guiding member.In some embodiments, the guiding member is adjustable to at leastpartially encircle at least one pulmonary vein.

In some embodiments, the tissue securing member includes at least oneconnector for removably coupling with the at least one energytransmission member. Sometimes, the tissue securing member isconformable to a surface topography of the heart tissue. In variousembodiments, a first longitudinal axis of the tissue securing member anda second longitudinal axis of the removably coupled energy transmissionmember may be collinear, parallel to one another or offset from oneanother. In some embodiments, the energy transmission member comprises alinear member, and the connector comprises a plurality of connectorsdisposed along a length of the tissue securing member for removablycoupling the linear member with the tissue securing member. The tissuesecuring member may allow compressive force to be applied between the atleast one energy transmission member and the heart tissue.

In some embodiments, the tissue securing member comprises at least onevacuum applying member. The vacuum applying member may comprise, forexample: at least one vacuum lumen; at least one vacuum port in fluidcommunication with the lumen for coupling the lumen with a vacuumsource; and at least one aperture in fluid communication with the lumenfor applying vacuum force to the heart tissue. In some embodiments, thevacuum lumen comprises multiple, separate lumens, and each separatelumen is in fluid communication with a separate vacuum port. Suchembodiments may optionally further include means for selectivelyapplying vacuum to one or more of the separate lumens without applyingvacuum to one or more other separate lumens. Alternatively or inaddition, the apparatus may be provided with suction pod plugs thatserve to occlude one or more of the suction apertures so that suction isapplied only through the remaining suction apertures that have not beenoccluded with a suction pod plug.

In other embodiments, the tissue securing member comprises at least oneexpansible balloon member. The expansible balloon member may include atleast one fluid introduction port for allowing introduction of a liquidor a gas to expand the balloon member. Some embodiments includemultiple, separate balloon members, wherein each separate balloon memberis in fluid communication with a separate fluid introduction port. Suchembodiments may also include means for selectively introducing fluidinto one or more of the separate balloons without introducing fluid intoone or more other separate balloons. Optionally, in some embodiments,the tissue securing member prevents a portion of the heart tissue frombeing treated by the at least one energy transmission member. Forexample, the tissue securing member may comprise at least one insulationmaterial for preventing the portion of the heart tissue from beingtreated. In one embodiment, the insulation material further prevents theat least one energy transmission member from contacting or harmingother, non-cardiac tissue of the patient and from contacting or harminga user of the energy transmission member.

In some embodiments, the guiding member comprises at least one of anelongate shaft, a steerable guidewire and an introducer sheath. Forexample, the steerable guidewire may comprise a pushable guidewirehaving at least one relatively stiff portion and one relatively flexibleportion for positioning the energy transmission member in a location fortreatment. For example, the steerable guidewire may comprise a pullableguidewire to which tension is applied to steer the guidewire to positionthe energy transmission member in a location for treatment.

In another aspect, a system for treating heart tissue to treat a cardiacarrhythmia comprises: at least one therapeutic agent transmission memberfor applying at least one therapeutic agent to the heart tissue in apattern to treat the cardiac arrhythmia; at least one tissue securingmember coupled with the at least one energy transmission member forenhancing contact of the energy transmission member with the hearttissue; and at least one guiding member coupled with at least one of theenergy transmission member and the tissue securing member for guidingthe energy transmission member and the tissue securing member to alocation for treating the heart tissue. In some embodiments, forexample, the therapeutic agent transmission member comprises at leastone lumen and at least one aperture in the lumen for allowing passage ofthe at least one therapeutic agent out of the lumen to contact the hearttissue.

Optionally, such a system may further include at least one needlecoupled with the therapeutic agent transmission member for insertioninto the heart tissue to enhance application of the at least onetherapeutic agent to the heart tissue. The therapeutic agenttransmission member itself may comprise at least one needle and at leastone aperture adjacent a tip of each needle for allowing passage of theat least one therapeutic agent out of the needle to contact the hearttissue. Optionally, the needle may be retractable. For example, theretractable needle may be exposed and retracted via a pneumatic membercoupled with the therapeutic agent transmission member. In someembodiments, the retractable needle is exposed and retractedautomatically when the therapeutic agent transmission member contactsthe heart tissue. Also in some embodiments, a depth of penetration ofthe retractable needle into the heart tissue is adjustable.

In another aspect of the invention, a method for treating heart tissueof a patient to treat a cardiac arrhythmia involves: advancing at leastone treatment member coupled with at least one tissue securing memberthrough an incision on the patient; visualizing a treatment area in thepatient with at least one visualization member; contacting the hearttissue of the patient with the treatment member and the tissue securingmember; applying a force, through the tissue securing member, to enhancecontact of the treatment member with the heart tissue; and treating theheart tissue, using the at least one treatment member. In someembodiments, the treatment member and/or the tissue securing member areadvanced through a port applied to the patient, the port having adiameter no greater than 5 cm.

In some embodiments, the advancing step includes guiding the treatmentmember and/or the tissue securing member using at least one guidingmember. Guiding may involve, for example, using a pushable guidewirehaving at least one relatively stiff portion and one relatively flexibleportion for positioning the treatment member in a location fortreatment. Alternatively, guiding may involve using a pullable guidewireto which tension is applied to steer the guidewire to position thetreatment member in a location for treatment.

Some embodiments of the method further include using at least onepositioning device to position the heart tissue for treatment. This mayinvolve, for example, applying suction to the heart tissue. In someembodiments, using the positioning device reduces motion of the hearttissue. In other embodiments, contacting the heart tissue comprisesapplying a suction force with the tissue securing member to increase acontact surface area of the tissue securing member with the hearttissue. Applying the suction force may further comprise providingconsistent contact force between the heart tissue and the tissuesecuring member. Optionally, applying the suction force may comprisesecuring the tissue securing member and the treatment member to theheart tissue, the tissue securing member and the treatment member havingthe same cross-sectional shape.

In some embodiments, treating the heart tissue comprises applying energyto the heart tissue in a pattern to reduce or eliminate the cardiacarrhythmia. The applied energy may be in any suitable form, such asradio frequency energy, ultrasound energy, microwave energy, cryogenicenergy, thermoelectric energy or laser energy. In some embodiments, theenergy is applied to an epicardial surface of the heart, wherein theenergy is transmitted from the epicardial surface through the hearttissue to an endocardial surface. Optionally, the energy may be furthertransmitted through fat and/or connective tissue covering at least partof the epicardial surface. Some methods may further include dispersingthe energy from the patient through at least one grounding devicecoupled with the patient.

Some embodiments further involve inserting at least one needle into theheart tissue to enhance the application of energy to the heart tissue.For example, the energy may transmitted from a tip of each needle. Somemethods include extending the at least one needle from a retractedposition before applying the energy and retracting the at least oneneedle to the retracted position when the energy has been applied. Suchmethods may also include selecting a depth of penetration of the atleast one retractable needle into the heart tissue. Other embodimentsmay involve measuring the application of energy to the heart tissueusing at least one closed circuit feedback loop and regulating theapplication of energy to the heart tissue based on the measurement.Still other embodiments may include applying fluid to the heart tissueto enhance the application of energy to the heart tissue.

In alternative embodiments, treating the heart tissue comprises applyingat least one therapeutic agent to the heart tissue in a pattern toreduce or eliminate the cardiac arrhythmia. For example, applying the atleast one therapeutic agent may involve infusing the agent through atleast one aperture in the at least one treatment member. In someembodiments, the therapeutic agent is infused through at least oneaperture in at least one needle coupled with the treatment member. Insome embodiments, applying the at least one therapeutic agent comprisesinserting at least one needle into the heart tissue to a desired depth,injecting the at least one agent into the heart tissue, and removing theat least one needle from the heart tissue. Such a method may furtherinclude extending the at least one needle from a retracted position forinsertion into the heart tissue and retracting the at least one needleto the retracted position after injection.

Yet another embodiment may include adjusting a shape of a guiding membercoupled with the at least one treatment member to alter the shape of thetreatment member. In some embodiments, adjusting the shape of theguiding member allows the treatment member to conform to a surface ofthe heart tissue. Also in some embodiments, adjusting the shape of theguiding member allows the treatment member to at least partiallyencircle at least one pulmonary vein. Some embodiments may also includeremovably coupling the tissue securing member with the at least onetreatment member. Some embodiments may further include conforming thetissue securing member to a surface topography of the heart tissue.

In some embodiments, applying force comprises applying compressive forcebetween the at least one treatment member and the heart tissue. Applyingthe compressive force, in turn, may comprise applying vacuum force viaat least one vacuum member of the tissue securing member. Such methodsmay further involve applying the vacuum force through at least a portionof the vacuum member while not applying the vacuum force through atleast another portion of the vacuum member. In some embodiments,applying the compressive force comprises applying force via at least oneexpansible balloon member. A method may further comprising preventing,using the tissue securing member, a portion of the heart tissue frombeing treated by the at least one treatment member. For example, thetissue securing member may comprise at least one insulation material forpreventing the portion of the heart tissue from being treated.

In some embodiments, visualizing comprises using at least onevisualization member selected from the group consisting of an opticimaging device, a thermal imaging device, an ultrasound device, anelectrical imaging device and a Doppler imaging device. Some embodimentsalso include expanding an expansible balloon coupled with thevisualization member near an optic element to enhance visualization.Sometimes, expanding the balloon provides a space in a body cavityand/or between at least two body tissues to enhance operation of theoptic member. Optionally, expanding the balloon may reduce motion of theheart tissue when applied to the heart tissue.

The invention also includes ablation systems which include an ablationenergy source for providing energy to the ablation device. The ablationenergy source of the invention is particularly suited for use withablation apparatus as described herein using RF energy, but is notlimited to such use, and other kinds of ablation energy sources andablation devices may be useable in the invention. A typical RF ablationsystem comprises a RF generator which feeds current to an ablationdevice, including those described in this application, containing aconductive electrode for contacting targeted tissue. The electricalcircuit is completed by a return path to the RF generator, providedthrough the patient and a large conductive plate, which is typically incontact with the patient's back.

In some embodiments, the ablation system is configured to recognize thekind of ablation device connected by including keyed plugs, whichdescribes specialized socket shapes configured to accept only plugswhich are manufactured with the matching shape. The energy sourceincludes predetermined settings appropriate for the kind of device thatis accepted by that socket. In another embodiment, the ablation systemof the invention includes apparatus for recognizing the kind of devicethat has been coupled to the energy source and for automaticallyadjusting various settings to accommodate the detected device.

In further embodiments the ablation device may be inserted minimallyinvasively under stress, and is configured to conform to the topographyor anatomy of the tissue to be treated when relaxed. This feature mayenhance the adherence of the ablation device to the tissue because thesuction is not working against resistance of the ablation device toconforming to the desired shape.

In other embodiments, the ablation device may include indicators foridentifying which ablation element is to be activated. For example, theablation device may include different colored lines to assist the userin distinguishing the orientation and alignment of the ablation device.

In some embodiments, the ablation device may be configured to allow theablation member to extend beyond the edge of the tissue contactingmember to allow for ablation to occur outside of the region covered bythe tissue contacting member.

In another embodiments, the artery securing arms may instead beconfigured to grasp a second ablation member, thereby allowing ablationto occur outside of the region covered by the tissue contacting member.

In some embodiments the length of the suction pods may be varied suchthat suction pods of more than one length are used on the same tissuecontact member. Furthermore, the suction pods may be spaced apart orplaced in groupings separated by selected lengths. Some or all of thelength of the ablation device used to emit ablation energy may notinclude any suction pods. In some embodiments an insulated member maycover the majority of the geometry of the ablation device such that onlyareas contacting target tissue can emit energy that will penetrate thetissue. This feature may protect surrounding tissues from unintentionalablation. Positioning the ablation member within an insulating tissuecontacting member provides a safety margin protecting adjacent tissuethat is not intended to be ablated. The insulated member may includelumens for delivering saline to lower impedance or increase conductivityor other substance to improve performance and efficiency of energyemission.

The suction force may be used to create a fluid gradient through thethickness of the tissue. A dynamic fluid gradient may enhance energyconduction.

In some apparatus and methods of the invention, once the tissue contactmember is positioned and suctioned onto the heart, the probe may also beslid within the probe channel in the tissue contact member so that theenergy emitting section of the ablation member may be positioned as aseparate step from the step of positioning the tissue contacting member.It is also possible to position the tissue contacting member separatelyfrom the ablation member, then in a later step, slide the ablationmember into the tissue contact member. In some embodiments, an ablationmember with a short energy emitting section may be moved along a channelin the tissue contact member so that the device can create long lesions,perhaps longer than the ablation section of the ablation member, withminimal manipulations of the device within the track.

Using a single placement of the tissue contacting member may enhancecontinuity of ablation lesions. Not having to move the ablation devicebetween discrete ablation cycles, and instead only moving the ablationmember within the tissue contacting member, insures that adjacentablation segments are contiguous with no ablation gaps. Avoiding thecreation of gaps can be critical to insure electrical isolation ofdesired tissue areas, and may also decrease procedure time by notrequiring the surgeon to verify overlap of adjacent ablation lesions.

In some embodiments the preferred features of the material used tomanufacture the tissue contacting member include one or more of thefollowing: the material provides electrical or thermal insulation, thematerial is flexible to facilitate remote advancement via tortuouspathways, the material has shape memory allowing large elasticdeformation of the tissue contacting member but also allowing the tissuecontacting member to return to a preformed shape in a relaxedconfiguration, the material may be translucent or transparent to helpthe user see the position of the ablation probe, and the material may belubricious to facilitate insertion and placement.

The method may further include the steps of using visual and audiblecues to verify the ablation device is adhered to tissue. For example theuser can hear a suction sound or ‘whistle’ when the suction has beenactivated and the ablation device is not correctly adhered. Also, theuser can hear vacuum pump elevate as vacuum increases. In someembodiments, the user can visually observe the tissue contacting membercollapse when the ablation device is correctly adhered and suction isactivated.

In some embodiments, the preferred vacuum pressure is −200 mmHG to −760mmHG.

In still further embodiments, the ablation device may include moreelectrodes that are available on the energy source. In this embodiment,the ablation device includes a plurality of electrodes, and wherein theenergy source includes fewer electrodes than the ablation device.Further, the ablation device includes at least two plugs, with each plugproviding power to a subset of the plurality of electrodes on theablation device. The method comprises the steps of connecting the firstplug of the ablation device to the energy source, applying ablationenergy to the tissue, unplugging the first plug from the energy source,plugging the second plug of the ablation device into the energy source,and applying ablation energy to the tissue.

This allows ablation device construction to facilitate longer ablationsby utilizing multiple connections to the energy source. For example, ifan energy source includes seven electrodes coupled to a single plug topower seven ablation segments on the ablation device, the ablationdevice could include fourteen or twenty-one separate ablation segments.Each set of seven ablation segments would couple to a separate plug. Inuse, the first plug is inserted into the energy source and the first setof seven ablation segments is activated. Upon completion of treatment,possibly without moving the ablation device, a second region may beablated by removing the first plug and inserting the second plug toactivate the next seven ablation segments on the ablation device. Thisembodiment can result in a smaller, less expensive energy source that isstill capable of powering a long ablation device.

In yet another aspect, a method for treating heart tissue of a patientto treat a cardiac arrhythmia comprises: advancing at least onetreatment member and at least one tissue securing member through anincision on the patient; removably coupling the at least one treatmentmember with the at least one tissue securing member; visualizing atreatment area in the patient with at least one visualization member;contacting the heart tissue of the patient with the treatment member andthe tissue securing member; applying a force, through the tissuesecuring member, to enhance contact of the treatment member with theheart tissue; and treating the heart tissue, using the at least onetreatment member. In some embodiments, and treatment member is advancedthrough the tissue securing member. Optionally, in some embodiments, thetreatment member and the tissue securing member are advanced through aminimally invasive port applied to the patient. Another method of theinvention includes the following steps. An introducer is advancedthrough a first incision into the transverse sinus cavity with obturatorfully inserted. At a desired area near the pulmonary veins, theobturator is withdrawn, which allows the introducer to assume itspre-formed J shape reaching around the pulmonary veins, possibly alsoguided by contact with the pericardium. The introducer is preferablylong enough to be inserted through a thoracotomy into the transversesinus cavity around the pulmonary veins and out through the obliquesinus and out through the same or a different thoracotomy. Anotherinstrument is advanced through the same or different thoracotomy tograsp the distal end of the introducer. The introducer is pulled aroundthe pulmonary veins until the distal end is outside the body of thepatient. At this point, both the proximal and distal ends of theintroducer are preferably outside the body of the patient. Once theablation device is in position, suction is applied to adhere theablation device to the tissue surrounding the pulmonary veins. Ablationenergy is applied. Once treatment is complete, the ablation device canbe removed.

Various embodiments of the devices and methods described briefly aboveare further described in the appended drawings and the followingdetailed description. The description of specific embodiments isprovided for exemplary purposes and should not be interpreted to narrowthe scope of the invention as defined in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustration of a human heart and anablation device in position for performing an ablation procedure,according to one embodiment of the invention.

FIG. 2 is a perspective view of an ablation device, according to oneembodiment of the invention.

FIG. 2 a is a perspective view of the ablation device shown in FIG. 2,with the ablation member removed.

FIG. 3 is a bottom-surface view of an ablation device, according to oneembodiment of the invention.

FIG. 4 is a perspective view of a flexible, elongate ablation devicewith two rows of suction apertures, according to one embodiment of theinvention.

FIG. 4 a is a bottom-surface view of the ablation device as shown inFIG. 4, with the ablation member removed.

FIG. 5 is a bottom-side view of a flexible, elongate ablation devicewith one row of suction apertures, according to one embodiment of theinvention.

FIGS. 5 a, 5 b, and 5 e are perspective views of another embodiment of aflexible, elongate ablation device with one row of suction apertures,separated by flexible joining members.

FIGS. 5 c and 5 d show several alternate cross sections of the flexiblejoining members of FIGS. 5 a and 5 b.

FIG. 6 is a perspective view of a human heart and an ablation device inposition for performing an ablation procedure, according to oneembodiment of the invention.

FIG. 7 is a perspective view of an elongate shaft ablation device,according to one embodiment of the invention.

FIG. 7 a is a perspective view of the distal end of a shaft as in FIG.6, with straight jaws, according to one embodiment of the invention.

FIG. 8 is a perspective view of a human heart and an elongate shaftablation device in position for ablating cardiac tissue, according toone embodiment of the invention.

FIG. 9 is a block diagram of a method for ablating tissue according toone embodiment of the invention.

FIG. 10 is an embodiment of the invention including an elongated tissuecontact member, built in accord with the invention.

FIG. 11 is an example embodiment of a power source built in accord withthe invention.

FIGS. 12 a and 12 b is an example of an ablation device in accord withthe invention, and an introducer for use with the ablation device.

FIG. 13 is an assembly drawing of an ablation device in accord with theinvention, and an introducer for use with the ablation device.

FIG. 14 is an exploded view showing the components of the ablationdevice of FIG. 13.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates generally to medical devices and methodsand more specifically to devices and methods for ablating cardiac tissuefor treating cardiac arrhythmias such as atrial fibrillation. Ablationof cardiac tissue in various patterns has been shown to disruptconduction pathways in the heart to ameliorate or eliminate AF or otherarrhythmias. The devices and methods will often be used to ablateepicardial tissue in the vicinity of at least one pulmonary vein, butvarious embodiments may be used to ablate other cardiac tissues in otherlocations on a heart.

Generally, ablation devices of the invention include at least one tissuecontacting member for contacting a portion of the epicardial tissue of aheart, securing means for securing the ablation device to the tissue andat least one ablation member coupled with the contacting member forablating at least a portion of the tissue. In various embodiments, thedevices have features which enable the device to attach to theepicardial surface with sufficient strength to allow the tissue to bestabilized via the device. For example, some embodiments may use suctionforce to secure the device to epicardial tissue and stabilize a beatingheart to enable a beating heart ablation procedure. In some embodiments,the preferred vacuum pressure is −200 mmHG to −760 mmHG. The suctionforce may be used to create a fluid gradient through the thickness ofthe tissue. A dynamic fluid gradient may enhance energy conduction.Other embodiments may include other optional features, such as sensorsfor sensing whether tissue has been ablated, a support member with anarm for connecting the device to a positioning device, cooling apparatusfor cooling epicardial tissue, visualization devices and/or the like.Some embodiments of the device are introducible into a patient viaminimally invasive means, such as a minimally invasive incision, sheath,trocar or the like. Ablation devices of the invention configured for usein minimally invasive procures will, in some embodiments, be longer thantwo feet the majority of the probe rests outside of the patient whilethe active ablation portion of the device is inserted via minimallyinvasive incision. Some embodiments will further comprise apparatus forreducing kinking of the ablation probe.

In alternate embodiments the length of the suction pods may be variedsuch that suction pods of more than one length are used on the sametissue contacting member. Furthermore, the suction pods may be spacedapart or placed in groupings separated by lengths of the probe orablation device. Some or all of the length of the ablation device usedto emit ablation energy may not include any suction pods. In suchembodiments an insulated member may cover the majority of the geometryof the ablation device such that only areas contacting target tissue canemit energy that will penetrate the tissue. This feature may protectsurrounding tissues from unintentional ablation. Positioning theablation member within an insulating tissue contacting member provides asafety margin protecting adjacent tissue that is not intended to beablated. The insulated member may include lumens for delivering salineto lower impedance or increase conductivity or other substance toimprove performance and efficiency of energy emission. In otherembodiments, the ablation device may include indicators for identifyingwhich ablation element is to be activated. For example, the ablationdevice may include different colored lines to assist the user indistinguishing the orientation and alignment of the ablation device.

The invention also includes ablation systems which include an ablationenergy source for providing energy to the ablation device. The ablationenergy source of the invention is particularly suited for use withablation apparatus as described herein using RF energy, but is notlimited to such use, and other kinds of ablation energy sources andablation devices may be useable in the invention. A typical RF ablationsystem comprises a RF generator which feeds current to an ablationdevice, including those described in this application, containing aconductive electrode for contacting targeted tissue. The electricalcircuit is completed by a return path to the RF generator, providedthrough the patient and a large conductive plate, which is typically incontact with the patient's back.

In some embodiments, the ablation system is configured to recognize thekind of ablation device connected by including keyed plugs, whichdescribes specialized socket shapes configured to accept only plugswhich are manufactured with the matching shape. The energy sourceincludes predetermined settings appropriate for the kind of device thatis accepted by that socket.

In another embodiment, the ablation system of the invention includesapparatus for recognizing the kind of device that has been coupled tothe energy source and for automatically adjusting various settings toaccommodate the detected device.

Methods of the invention generally include contacting a device withepicardial tissue, using a tissue contacting member on the device tosecure the device to the tissue, and ablating the tissue with anablation member on the device. In some embodiments, the method furtherincludes additional steps such as positioning the device on theepicardial tissue, stabilizing cardiac tissue, cooling cardiac tissue,positioning the device using a positioning device, visualizingepicardial tissue with an imaging device and/or the like. Again,although much of the following description focuses on embodiments usedto treat AF by ablating epicardial tissue near one or more pulmonaryveins on a human heart, the devices and methods may be used inveterinary or research contexts, to treat various heart conditions otherthan AF, to ablate cardiac tissue other than the epicardium and/or inany other suitable manner or context.

Referring now to FIG. 1, an ablation device 100 is shown in position forablating epicardial tissue on a human heart 140. A top view of ablationdevice 100 is shown, the visible components of device 100 including atissue contacting member 102 coupled with a suction connector 216 and asupport member 104 having a support arm 106. Tissue contacting member102 also includes multiple artery securing arms 108 for securing one ormore coronary arteries. Suction connector 216 is coupled with a suctioncannula 112, which in turn is coupled with a suction source 120. Supportarm 106 is coupled via a clamp 116 to a positioner 114, which in turn iscoupled to a stabilizing device 118 for stabilizing positioner 114.Finally, an ablation member (not visible) of ablation device 100 iscoupled, via a wire 110, to an energy source 122. In variousembodiments, ablation device 100 may be introduced into a patientthrough a minimally invasive introducer device, such as a sheath 124,trocar or the like, as is represented in FIG. 1 by a simplifiedrepresentation of sheath 124.

In an alternate embodiment, the artery securing arms 108 may instead beconfigured to grasp a second ablation member, thereby allowing ablationto occur outside of the region covered by the tissue contacting member.In this embodiment the features 108 are instead auxiliary securing arms.Although example auxiliary securing arms are shown only in FIG. 1, thisfeature could be used on other ablation device embodiments.

In FIG. 1, ablation device 100 is shown in a position partiallyencircling the right superior pulmonary vein 142 and the right inferiorpulmonary vein 144. As will be described in further detail below, such aposition is only one possible configuration for treating heart 140. Inother embodiments, for example, both of the right pulmonary veins 142,144 may be completely encircled, only one may be partially or completelyencircled, the left superior 148 and/or left inferior 150 pulmonaryveins may be partially or completely encircled and/or various patternsmay be ablated on the left atrium 146, the right atrium 152 and/or theright and left ventricles (not labeled). Any ablation pattern suitablefor heart treatment may be accomplished by one or more embodiments ofthe present invention. Thus, the following descriptions of variousembodiments should not be interpreted to narrow the scope of theinvention as set forth in the claims.

Generally, ablation device 100 includes at least one tissue contactingmember 102 coupled with at least one ablation member (not shown in FIG.1). One embodiment of a device which may be used as tissue contactingmember 102 is described in U.S. patent application Ser. No. 60/182,048,filed on Feb. 11, 2000, the entire contents of which is herebyincorporated by reference. Ablation device 100 shown in FIG. 1 actuallyincludes two tissue contacting members 102, one on either side of theright pulmonary veins 142, 144. Tissue contacting members 102 may becoupled together via support member 104 and suction connector 216. Inother embodiments, some of which will be described below, tissuecontacting member 102 may include only one member, more than twomembers, a coupling member disposed between multiple arms and/or thelike. Alternatively, tissue contacting member 102 may be conical,linear, shaped as a flat pad or a flat elongate member or may have anyother suitable configuration. Additionally, tissue contacting members102 may have any suitable size and dimensions. For example, in FIG. 1,tissue contacting members 102 and device 100 in general have a shape anddimensions to contact and ablate epicardial tissue on heart 140 in apattern partial encircling the right pulmonary veins 142, 144. Manyother configurations and sizes are possible, as described further below.

Tissue contacting members 102 may be manufactured from any suitablematerial, such as a polymer, plastic, ceramic, a combination ofmaterials or the like. In one embodiment, for example, tissue contactingmembers 102 are manufactured from a liquid molded rubber. In someembodiments, the material used to make tissue contacting members 102 ischosen to allow the members 102 to be at least partially deformable ormalleable. Deformable tissue contacting members 102 may allow ablationdevice 100 to be inserted into a patient and/or advanced to a surgicalsite within the patient via a minimally invasive incision or a minimallyinvasive introducer device, such as sheath 124. Deformable tissuecontacting members 102 may also allow device 100 to conform to a surfaceof heart 140, to enhance ablation of epicardial or other cardiac tissue.In some embodiments, tissue contacting members 102 include one or moreartery securing arms 108, for securing, exposing and/or occluding one ormore coronary arteries via silastic tubing attached between the arteryand securing arm 108. Securing arms 108 are generally made of the samematerial(s) as tissue contacting members 102 but may also suitablycomprise other materials.

In some embodiments the ablation device may be inserted minimallyinvasively under stress, and is configured to conform to the topographyor anatomy of the tissue to be treated when relaxed. This feature mayenhance the adherence of the ablation device to the tissue because thesuction is not working against resistance of the ablation device toconforming to the desired shape.

Thus, some embodiments the preferred features of the material used tomanufacture tissue contacting member 102 may further include one or moreof the following characteristics: the material provides electrical orthermal insulation, the material is flexible to facilitate remoteadvancement via tortuous pathways, the material has shape memoryallowing large elastic deformation of the tissue contacting member butalso allowing the tissue contacting member to return to a pre-formedshape in a relaxed configuration, the material may be translucent ortransparent to help the user see the position of the ablation probe, thematerial may be lubricious to facilitate insertion and placement, andthe material allows thin walled construction of the tissue contactingmember so that collapse of the tissue contacting member can be seen toconfirm the operation of the vacuum when activated.

In some embodiments, tissue contacting members 102 are coupled withsupport member 104. Support member 104 may be made of any suitablebiocompatible material, such as titanium, stainless steel, nickeltitanium alloy (Nitinol) or the like. Support member 104 may be coupledwith tissue contacting members 102 by any suitable means, such as butnot limited to one or more adhesive substances, placement of a portionof support member 104 within a sleeve on tissue contacting members 102or a combination of both. Like tissue contacting members 102, supportmember 104 may also be malleable or deformable to allow for insertion ofablation device 100 through a minimally invasive sheath 124 and/or forenhancing conformability of device 100 to a surface of heart 140.Support member 104 typically includes at least one support arm 106 orsimilar protrusion or multiple protrusions for removably couplingablation device 100 with positioner 114 or one or more other positioningdevices. Positioner 114, for example, may comprise a flexible,positioning arm, with attachment means such as clamp 116 for attachingto support arm 106 and stabilizing device 118 for stabilizing positioner114. For example, a flexible, articulating positioner 114 may be of thetype which rigidities when tensile force is applied, such as via atensioning wire. Any other suitable positioner 114 may alternatively beused. In other embodiments, device 100 may not include support member104. Such devices 100 may incorporate a connection arm onto a tissuecontacting member 102, may be positioned on heart 140 using apositioning device inserted through a separate incision, or may bepositioned or manipulated by a physician or other user via any othersuitable means.

Tissue contacting members 102 may also be coupled with one or moresuction cannulas 112 to provide suction for enhancing contact ofablation device 100 with epicardial tissue. In various embodiments,tissue contacting members 102 may be directly coupled to one or morecannulas 112 or may be connected via one or more suction connectors 216.In FIG. 1, a V-shaped suction connector is used to couple the two tissuecontacting members 102 with a common cannula 112. Cannula 112, in turn,is connected to suction source 120, which may be a conventional wallsuction or stand-alone suction source. Generally, cannula 112 may be anysuitable conventional cannula 112, which are well known to those skilledin the art. Suction connector 216 is typically comprised of the samematerial(s) as tissue contacting members 102, but may also be made of amaterial or materials used to make cannula 112. Suction connector 216may further include a nozzle 218 (FIG. 2) for connecting to cannula 112.

Ablation device 100 also includes at least one ablation member 210 (FIG.2). Ablation member 210 typically receives energy from a separate energysource 122, although ablation members 210 with internal energy sourcesare also contemplated. Where a separate energy source 122 is used,ablation member 210 may be coupled with source 122 by any suitablemeans. In one embodiment, for example, ablation member 210 may becoupled to energy source 122 with wire 110. Wire 110 may be any suitableconnector, such as fiber optic cable, electric cable, coaxial cable,ultrasound transmission device or the like. As is described furtherbelow, any suitable energy may be provided by energy source 122 forablation and any means for transmitting energy to ablation member 210 iscontemplated within the scope of the invention. In some embodiments, forexample, energy may be transmitted remotely, so that no wires or othersimilar connecting devices are required. In other embodiments, radiofrequency energy may be provided by an RF energy source and transmittedto ablation member 210 via conventional electrical wire(s) 110.

Generally, ablation member 210 may be configured to transmit energy ofany suitable quantity or force. For example, in some embodimentssufficient energy will be transmitted through ablation member 210 toablate only epicardial tissue on a heart. In other embodiments,sufficient energy may be transmitted to cause one or more layers beneaththe epicardial tissue to be ablated. In some embodiments, for example,one or more transmural lesions (across the entire wall of the heart) maybe ablated. Typically, an amount of energy transmitted through ablationmember 210 will be adjustable to create a desired ablation depth. Inaddition, the depth of ablation can also be affected by the contactpressure between the ablation member 210 and the tissue. Generally, thegreater the contact pressure between the ablation member 210 and thetissue the deeper the ablation lesion will extend into the tissue. Thecontact pressure can be adjusted to a desired level by adjusting themechanical force applied through the tissue contacting members 102and/or by adjusting the level of suction applied through the suctionapertures 212.

In addition, the contact pressure between the ablation member 210 andthe tissue gives a degree of directional control over the direction thelesion ablation lesion will extend into the tissue. Only the tissue incontact with the ablation member 210 and in a direction perpendicular tothe surface of the tissue will be ablated. Adhering the ablation member210 to the target tissue with suction applied through the suctionapertures 212 assures that only the intended tissue will be ablated andwill prevent migration or rollover of the tissue contacting members 102and ablation member 210.

In this example and other embodiments disclosed herein, the suctionapertures 212 may be connected to multiple, separate suction lumens.Optionally, the apparatus may include means for selectively applyingvacuum to one or more of the separate lumens without applying vacuum toone or more other separate lumens. Alternatively or in addition, theapparatus may be provided with suction pod plugs that serve to occludeone or more of the suction apertures 212 so that suction is applied onlythrough the remaining suction apertures 212 that have not been occludedwith a suction pod plug.

As mentioned briefly above, a minimally invasive introducer sheath 124,trocar or other minimally invasive device may be used for introducingone or more of the components shown in FIG. 1 into a patient. In someembodiments, a sheath need not be used and instead only a minimallyinvasive incision is used. In other embodiments, multiple minimallyinvasive incisions and/or sheaths 124 may be used for introducingvarious devices into a patient. For example, one sheath 124 may be usedfor introducing ablation device 100 and another sheath 124 may be usedfor introducing positioner 114. Although devices and methods of thepresent invention are often suitable for minimally invasive procedures,they may also typically be used in open surgical procedures, either withor without cardiopulmonary bypass, in various embodiments.

Referring now to FIG. 2, an embodiment of ablation device 100 is shownin further detail. Device 100 is shown from a bottom/angled view to showa tissue contacting surfaces 224 of tissue contacting members 102,ablation member 210, suction apertures 212 and sensors 214. Like tissuecontacting members 102, tissue contacting surfaces 224 may be given anyconfiguration and sizes to contact cardiac tissue in an area around thetissue to be ablated. For example, in an embodiment as in FIG. 2 atissue contacting surface 224 on one tissue contacting member 102 mayhave a length of approximately 1.25 in. and a width of approximately 0.5in., with a space between the two tissue contacting surfaces measuringapproximately 0.4 in. Such exemplary dimensions are in no way limiting,and all combinations of dimensions for one or more tissue contactingmembers 102 are contemplated. In some embodiments, as in FIG. 2,surfaces 224 may be flat and smooth. In other embodiments, surfaces 224are textured, curvilinear or otherwise shaped to enhance contact oftissue contacting members 102 with heart 140. Some embodiments mayfurther include one or more surface features 222. Such features 222 mayenhance friction between tissue contacting surfaces 224 and epicardialtissue and/or may provide an area for placement of additional features,such as irrigation apertures for cooling tissue or the like.

Ablation member 210 may include one or more ablation members fortransmitting one or more of a variety of ablation agents to epicardiumor other cardiac tissue. In some embodiments, as commonly shown in thedrawing figures, ablation member 210 may comprise a single, continuous,RF ablation coil or wire for transmitting RF energy to cardiac tissue.In other embodiments, ablation member 210 may be multiple radiofrequency devices or one or more cryogenic devices, ultrasound devices,laser devices, thermo-electric chip devices, chemical agent deliverydevices, biological agent delivery devices, light-activated agentdevices, thermal devices, microwave devices, or ablating drug deliverydevices. Other suitable ablation devices are also contemplated withinthe scope of the invention. Additionally, radio frequency ablationmembers 210 may be bipolar or unipolar in various embodiments. Inconjunction with any of these various embodiments, energy source 122 mayprovide any of the above-listed types of ablative energy or substance,any combination thereof or any other suitable ablative energy orsubstance.

Ablation member 210 may be given any configuration or size for ablatingcardiac tissue. In the embodiment shown in FIG. 2, for example, ablationmember 210 has two linear portions disposed along most of the lengths ofcontacting surfaces 224 of tissue contacting members 102, and the linearportions are continuous with a curved portion 226 so that ablationmember 210 is generally U-shaped. Alternatively or additionally,ablation member 210 may continue proximally from tissue contactingmembers 102 in one or more arms 230 which eventually connect to wire 110or other connective device. In some embodiments, curved portion 226 maybe eliminated so that ablation member 210 comprises two linear ablationmembers connected to wire 110 via arms 230. In yet other embodiments,arms 230 may be eliminated and ablation member 210 may be coupleddirectly to wire 110 without interposing arms.

Generally, ablation members 210 and tissue contacting member 102 mayhave any shapes, sizes, configurations or combinations of shapes andsizes to produce a desired ablation pattern on epicardial or othertissue of a heart. In some examples, ablation members 210 and tissuecontacting members 102 are configured to partially or completelyencircle or surround one pulmonary vein. In other embodiments, they maybe configured to partially or completely surround two pulmonary veins onthe same side of the heart, such as the left superior and left inferiorpulmonary veins. In still other embodiments, the right and left inferiorpulmonary veins or the right and left superior pulmonary veins may bepartially or wholly encircled. And in still other embodiments, all fourpulmonary veins may be partially or completely encircled by ablationmembers 210 and tissue contacting member 102. Some of these embodimentsare described in further detail below, but it should be understood thatany possible configuration is contemplated within the scope of thepresent invention.

In some embodiments, all or a portion of ablation member 210 or tissuecontacting member 102 may be steerable. Steerability means that anablation member 210 or tissue contacting member 102 may be adjusted tofit around or next to one or more pulmonary veins or to otherwise assumea desired configuration. For example, some embodiments may include apull wire coupled with ablation member 210 and/or tissue contactingmember 102. The pull wire, when pulled, deflects ablation member 210and/or tissue contacting member 102 to one side or around a curvedstructure. Other embodiments may include pushable wires, combinations offlexible and stiff portion and/or the like to provide steerability.

In some embodiments, for example, it is desirable to ablate epicardialtissue in a circumferential pattern around one or more pulmonaryarteries. Various configurations of tissue contacting members 102 andablation members 210 are contemplated for achieving such ablationpatterns. For example, a retractable RF coil 240 or other retractableablation device may be incorporated into or used in conjunction withablation member 210 as shown in FIG. 2. Retractable coil 240 could behoused within tissue contacting member 102, for example, and could bereleased when desired to surround or encircled one or two pulmonaryveins. As already described, the RF ablation member 210 and/or the RFretractable coil 240 pictured in FIG. 2 may be replaced, in otherembodiments, with devices using radio frequency energy, ultrasoundenergy, microwave energy, cryogenic energy, thermoelectric energy orlaser energy for ablating tissue. For example, ablation member 210 insome embodiments comprises multiple thermoelectric chips disposed in apattern on tissue contacting members 102.

Although ablation device 100 and ablation member 210 are often shown asbeing generally U-shaped, many other configurations are possible. Asdescribed further below, a ablation device 100 may be conical in shape,with ablation member 210 being disposed in a circle at the base of thecone which contacts cardiac tissue. In other embodiments, device 100 maybe configured as a flat patch and one or more linear or curvilinearablation members 210 may be incorporated into the patch. For example,ablation device 100 may include a combination of multiple ablationmembers 210 to ablate a pattern on heart 140 such as: a first linearablation member for contacting heart tissue between a left pulmonaryvein and a right pulmonary vein; a second linear ablation member forcontacting heart tissue at a location approximating a line extending tothe atrioventricular groove; and a third linear ablation member forcontacting heart tissue on a left atrial appendage. In such anembodiments, one or more of ablation members 210 may overlap oneanother. In some embodiments involving multiple ablation members 210,each member may be controllable on a separate radio frequency channel orother energy transmission channel.

Tissue contacting members 102 optionally include one or more attachmentmeans for enhancing contact of ablation device 100 with epicardial orother cardiac tissue. In some embodiments, one or more suction apertures212 are used. Each suction aperture 212 generally includes a depressedsurface and a small suction hole. The suction hole is connected to alumen (not shown) within tissue contacting member 102, and the lumen isthen couplable with a suction cannula 122 or connector 216 forconnecting to cannula 122. Suction apertures 212 may be given anysuitable configuration, size or pattern. For example, suction holes maybe disposed on tissue contacting member 102 is a largely linear pattern,as in FIG. 2. In other embodiments, suction apertures may be arranged intwo parallel lines such that ablation member 210 is disposed between thetwo parallel lines of suction apertures 212. In still anotherembodiment, ablation device 100 may include one tissue contacting member102 having a conical shape, with the base of the cone contactingepicardial tissue and the entire conical tissue contacting member 102acting as one suction aperture.

In some embodiments, suction force may be applied via suction apertures210 with sufficient strength to allow for stabilization and/orpositioning of heart 140. For example, a physician may place ablationdevice 100 on a beating heart 140, apply suction, and hold heart 140 isa relatively stable or reduced-motion position while performing anablation procedure. The physician may also (or alternatively) turn orotherwise move heart 140, using ablation device 100, such as when adifferent angle of heart 140 would be advantageous for viewing ortreating a portion of heart 140. In these or other embodiments, suctionforce applied through suction apertures 212 may be of sufficientstrength to dissect through one or more layers of adipose tissuecovering epicardial tissue. Such dissection by suction apertures 212 mayallow for improved contact of the epicardial tissue by device and, thus,improved ablation. In alternative embodiments, suction apertures 212 maybe replaced or supplemented by other means for securing ablation device100 to epicardial tissue. For example, an adhesive may be applied totissue contacting surfaces 224. Such adhesives or other securing meansmay also be sufficiently strong, in some embodiments, to allow forpositioning and/or stabilization of heart 140.

Referring to FIG. 2, tissue contacting members 102 may also include oneor more sensors 214 for judging the thickness of the tissue or todetermine the amount of therapy or energy that must be delivered to thetissue, for sensing whether the ablation device 100 is properlypositioned in contact with the tissue to be ablated, and to monitor theprogress of the ablation to recognize when the tissue along a selectedlength of the ablation device 100 has received sufficient treatment andcommunicates with a means for directing the ablation device 100 todiscontinue or reduce treatment at that site; in some embodiments, whilecontinuing to apply ablation energy at other locations along the lengthof the ablation device 100. For these and other purposes, the sensors214 may include one or more thermal sensors, electrical sensors,thermoelectric sensors, microchips, thermistors, thermocouples, Dopplersensors, microwave sensors, and ultrasonic sensors.

As shown in FIG. 2, some embodiments include two or more paired sensors214, with one sensor of each pair on one side of ablation member 210 andthe other sensor on the opposite side. In some embodiments, one sensor214 transmits a signal through epicardial tissue to its paired sensor214. If epicardial tissue between the two paired sensors 214 has beenablated, then energy will transmit poorly through that ablated tissue.Thus, the receiving sensor 214 will receive reduced or no energytransmitted from the transmitting sensor 214. If tissue between twopaired sensors has not been ablated, the signal should travel throughthe tissue with only slight reduction in strength. By using such pairedsensors 214 and comparing signals received in different pairs, areas ofablation can be compared, to determine if all desired areas for ablationhave been sufficiently ablated. Other configurations one or more sensors214 may also be used.

Referring now to FIG. 2 a, another view of ablation device 100 as inFIG. 2 is shown, with ablation member 210 removed for clarity. In someembodiments, tissue contacting members 102 include a linear trough 250in which ablation member 210 is placed, either removably or permanently.Positioning ablation member 210 in trough 250 may provide improvedcontact between ablation member 210 and epicardial tissue while alsoproviding ablation device 100 with durability. Surface features 222 areagain shown in FIG. 2 a. These features may simply enhance contact oftissue contacting members 102 with epicardial tissue or may also containadditional features, such as sensors, irrigation apertures for allowingpassage of irrigation fluid for cooling ablated tissue, small suctionapertures and/or the like.

Optionally, various embodiments of ablation device 100 may furtherinclude at least one cooling member for cooling a portion of ablatedepicardial tissue, epicardial tissue surrounding an ablated area, othernearby tissues and/or a portion of device 100. Cooling members are notshown in the drawing figures, for purposes of clarity. Generally, acooling member may comprise any suitable device for cooling a tissue. Insome embodiments, cooling member includes at least one inlet port, forallowing introduction of a cooling substance into the member, a hollowinternal cooling member, and at least one outlet port for allowingegress of the cooling substance. The cooling substance itself may becarbon dioxide, any other suitable gas, saline or any other suitableliquid. In some embodiments, the hollow cooling member comprises atubular member disposed within tissue contacting member 102 in generalproximity with ablation member 210. In other embodiments, cooling membermay comprise a chamber for containing cooling substance or a series ofirrigation holes for allowing cooling substance to flow out of tissuecontacting member 102 to contact ablated or other epicardial tissue.Many other suitable cooling apparatus are contemplated for use withinthe scope of the present invention.

With reference now to FIG. 3, another embodiment of ablation device 300is shown from a bottom-side view. Ablation device 300 includes a tissuecontacting member 302, coupled with an ablation member 310 and a supportmember 304. As with some above-described embodiments, tissue contactingmember includes a tissue contacting surface 324, tissue attaching meansincluding multiple suction apertures 312 and multiple artery securingarms 308. Tissue contacting member 302 is removably couplable with asuction cannula 318 via a V-shaped suction connector 316. Ablationmember 310 is coupled with energy transmitting wire 314 for couplingwith an energy source (not shown). Support member 304 includes a supportarm 306 (shown partially in dotted lines, since it extends on theopposite side of tissue contacting member 302) for coupling device 300with a positioning device.

In ablation device 300, tissue contacting member 302, ablation member310 and support member 304 are all generally shaped as a square with acentral area 303 and a top area 305 left open. Such a configuration maybe used, for example, to contact and ablate epicardial tissue almostcompletely encircling one or more pulmonary veins. Leaving top area 305open may allow device 300 to be positioned around such veins or othervessels while still providing almost circumferential ablation. In otherembodiments, either central area 303, top area 305 or both may be closedto provide for different contact and/or ablation patterns on epicardialtissue. In still other embodiments, one or more hinges may be positionedon ablation device 300 to allow top area 305 to be closed afterpositioning device 300 around one or two pulmonary veins. Again, anyconfiguration, shape, size, dimensions or the like are contemplatedwithin the scope of the invention.

Referring now to FIG. 4, another embodiment of ablation device 400comprises a largely flexible device which includes a tissue contactingmember 402 and an ablation member 410. Tissue contacting member 402 maybe made of any suitable, flexible material, such as a silicone,polyurethane, polycarbonate, another suitable polymer or combination ofpolymers or the like. Tissue contacting member 402 generally includes atissue contacting surface 424 having multiple suction apertures 412.Tissue contacting surface 424 may be slightly concave (as shown), flator may have any other suitable shape. Suction apertures 412 are disposedin two parallel lines, one line on either side of ablation member 410and communicate with suction lumens 414 and 416. Suction lumens 414, 416may be coupled with one or more suction cannulas or similar devices forproviding suction force through suction apertures 412. Other embodimentsmay include one common suction lumen for connection to a suctioncannula.

As with various embodiments described above, any suitable ablation meansmay be used as ablation member 410 in device 400. In the embodimentshown, ablation member 410 comprises a linear radio frequency coil.Ablation member 410 may extend beyond the length of tissue contactingmember 402, either in a proximal or distal direction and may be coupledwith a source of energy via a wire (not shown) or other connectiondevice. In various embodiments, one or more of the features describedabove, such as support members, retractable ablation elements, sensors,cooling members, positioning arms and/or the like may be incorporatedinto or used with ablation device 400. Alternatively, ablation device400 may simply include tissue contacting member 402 and linear ablationmember 410. Such an embodiment may be advantageous for introductionthrough a narrow, minimally invasive introducer sheath, due to thedevice's flexibility and relatively small size. In one embodiment, forexample, device 400 may measure approximately 3.25 in. in length andapproximately 0.9 in. wide and may further be deformable to a narrowerconfiguration for insertion through a sheath. Furthermore, device 400may be sufficiently flexible to conform to curved surfaces of heart 140,allowing for enhanced contact with and ablation of epicardial tissue.Finally, it may sometimes be advantageous to ablate epicardial tissue ina linear pattern or in multiple line. Ablation device 400 may bemovable, to allow ablation in a first line, a second line, a third lineand/or the like.

Referring now to FIG. 4 a, a bottom-side view of ablation device 400 isshown with ablation member removed. It can be seen that tissuecontacting member 402 may include a trough 420 in which ablation member410 may be positioned. In some embodiments, ablation member 410 may be aremovable piece which may be removably attached to tissue contactingmember 402, at least partially disposed within trough 420, so that oneablation member 410 may be used with multiple tissue contacting members402, one after another, for example if tissue contacting members 402 aresingle-use, disposable devices.

In some apparatus and methods of the invention, once the tissue contactmember is positioned and suctioned on to the heart, the ablation device400 may also be slid within the trough 420 in the tissue contact member402 so that the energy emitting section of the ablation member 410 maybe positioned as a separate step from the step of positioning the tissuecontacting member 402. It is also possible to position the tissuecontacting member 402 separately from the ablation member 410, then in alater step, slide the ablation member 410 into the tissue contact member401. In some embodiments, an ablation member 410 with a short energyemitting section may be moved along a trough 420 in the tissue contactmember 401 so that the ablation device 400 can create long lesions,perhaps longer than the ablation section of the ablation member 410,with minimal manipulations of the device within the track.

Using a single placement of the tissue contacting member may enhancecontinuity of ablation lesions. Not having to move the ablation devicebetween discrete ablation cycles, and instead only moving the ablationmember within the tissue contacting member, insures that adjacentablation segments are contiguous with no ablation gaps. Avoiding thecreation of gaps can be critical to insure electrical isolation ofdesired tissue areas, and may also decrease procedure time by notrequiring the surgeon to verify overlap of adjacent ablation lesions

FIG. 5 shows yet another embodiment of ablation device 500, including atissue contacting member without an ablation member being shown. Device500 is similar to ablation device 400, but tissue contacting member 502has one row of suction apertures 512 rather than two and ablationmember, placed in ablation trough 520, overlays suction apertures 512.Suction holes 522 shown in suction apertures 512 demonstrate that theapertures sometimes include both a depressed or concave surface and oneor more holes communicating with a suction lumen. The embodiment ofablation device 500 in FIG. 5 may be advantageous for forming one ormore linear ablations on heart 140 when there is minimal space in whichto manipulate device 500 and/or when a narrow, minimally invasiveincision or sheath is desired for insertion of device 500. Device 500may be manufactured from any suitable material or combination ofmaterials, such as those described above, may use any suitable form ofablation member and may include various additional features as desired.

FIG. 5 a is a bottom perspective view of an alternate another embodimentsuction pods 524 spaced some distance apart and joined by a flexiblejoining members 526, which may also be used to provide a channel for avacuum lumen. The distance between the suction pods 524 and theflexibility of the joining members 526 between the suction pods 524 hasbeen found to increase the ability of the tissue contacting member 502to bend in sharp turns. In FIGS. 5 a and 5 b, the joining members 526are cylindrical in cross section, which may improve the overallflexibility of the ablation device 500 in all directions. Theflexibility can be varied as desired by changing the thickness, shape,and size of the joining members 526 between the suction pods 524, and byvarying the flexibility of the material used to fabricate the joiningmembers 526. For example, FIGS. 5 c and 5 d show example alternatejoining member 526 cross sections. The square cross section of FIG. 5 cmay allow bending in X and Y axes, but may resist axial rotation. Theexample cross section shown in FIG. 5 d may allow bending in a downwardvertical direction, but may resist bending in lateral directions. FIG.5E shows an ablation member 528 including ablation segments 530configured for insertion of tissue contacting member 502.

Referring now to FIG. 6, ablation device as described with reference toFIGS. 4 and 4 a is shown in position for performing epicardial ablationon a human heart 140. Generally, ablation device 400 may be placed inany desired position on heart 140 for ablating epicardial tissue. Thus,in various embodiments device may be placed adjacent one or both of theright pulmonary veins 142, 144, adjacent one or both of the leftpulmonary veins 148, 150, or in any other suitable location.Furthermore, ablation device 400 may be used to ablate tissue in alinear pattern at one location and then may be moved to ablated tissuein a linear pattern in another location. As discussed above withreference to various embodiments, ablation device 400 may be introducedinto a patient via a minimally invasive device, such as a sheath 630 ortrocar, and may be coupled with a source of suction 120 via a suctioncannula 112 and with a source of ablative energy 122 via a wire 110 orother connective device.

Ablative device 400, as well as other embodiments of ablative devicesdescribed above, may be positioned on heart 140 via a positioning device602 which is introduced via a second minimally invasive incision orsecond sheath 620. Second sheath 620 may be placed at any suitablelocation on the patient to allow access to ablation device with thepositioning device 602. Positioning device 602 may then be introducedthrough sheath and advanced to the position of ablation device 400.Positioning device 602 may then be used to secure device 400, such as byopposable jaws 610 or any other suitable means, and position device 400in a desired location on heart 140. In some embodiments, positioningdevice may further be used to reposition device 400 to perform ablationin multiple locations on heart 140. The proximal end of positioningdevice 602 may include a handle 604 for holding and manipulating device602 and one or more actuators 606, such as a trigger for opening andclosing opposable jaws 610 or other distally positioned end effectors ofdevice 602. Examples of positioning device 602 may include, but are notlimited to, conventional minimally invasive surgical devices such aslaproscopic surgical devices and the like.

Referring now to FIG. 7, another embodiment of ablation device 700suitably includes at least one elongate shaft 702 having a proximal end724 and a distal end 726, a jaw member 704 coupled with shaft 702 neardistal end 726, at least one ablation member 712, 714 coupled with jawmember 704, and a handle 706 and at least one actuator 708, 710 near theproximal end 724 for manipulating device 700, opening and closing thejaw member, activating ablation member 712, 714 and the like. Device 700is generally configured to be introduced through a minimally invasivesheath, trocar or incision, though it may also be used in open surgicalprocedures. Shaft 702 may be made of any suitable material, such asmetal, ceramic, polymers or any combination thereof, and may be rigidalong its entire length or rigid in parts and flexible in one or moreparts. In various embodiments, the shaft may be malleable, mayarticulate about at least one joint and/or may be steerable forpositioning the device. In some embodiments, the ablation member iscoupled with a portion of the shaft.

Jaw member 704 may be disposed on or near distal end 726 of shaft 702and is generally configured to open and close to grasp epicardial orother tissue between the opposing jaws. For example, jaw member 704 maybe coupled with shaft 702 at a hinge point 730 to allow for such openingand closing motion. An ablation member is coupled with at least part ofjaw member 704. As with the above-described embodiments, the ablationmember may use any suitable energy source for ablating tissue. In someembodiments, multiple ablation members 712, 714 may be used. Forexample, one electrode 712 of a bipolar ablation member may be coupledwith one opposing jaw and another electrode 714 may be coupled with theother opposing jaw. Alternatively, ablation members 712, 714 may includeone unipolar ablation device or any of the ablation devices describedwith reference to various embodiments above. The jaw member and/or theablation member may be shaped to contact and ablate the epicardialtissue in a pattern such as, but not limited to, a U-shaped pattern, anL-shaped pattern, a circular pattern or a linear pattern. Actuators 708,710 may have one or more various functions, such as opening and closingjaw member 704, activating ablation members 712, 714, changing an angleof orientation of jaw member 704, straightening or bending jaw member704 and/or the like. One actuator 710, for example, may comprise atrigger-like actuator while another actuator 708 may comprise a turnabledial.

Generally, jaw member 704 may have any suitable configuration forcontacting a surface of a heart, for grasping epicardial or other tissueto be ablated and/or for placing ablation members 712, 714 in contactwith tissue to be ablated. As such, jaw members 714 may be straight,curved, bent or otherwise configured for contacting, grasping and/orablating tissue. In some embodiments, jaw member 704 may be adjustablevia an actuator 708, 710, so as to allow their shapes to be bent,straightened or the like during a procedure. With reference to FIG. 7 a,one embodiment of a straight jaw member 718 may allow jaw member 718 tobe retracted within shaft (arrows). Retraction may help protect apatient as well as jaw member during insertion and advancement of thedevice within the patient. Again, ablation members 720, 722 on suchstraight jaw members 718 may be bipolar RF members, unipolar RF membersor any other suitable ablation devices.

Optionally, the device may further include an insulation member at leastpartially surrounding the device to protect body structures in thevicinity of the epicardial tissue to be ablated from damage due to heator electrical current. Also optionally, the ablation member may beadjustable to deliver two or more varying amounts of ablative energy totwo or more locations on the epicardial tissue. Various embodiments mayfurther include at least one sensor for sensing a quantity of ablationprovided by the ablation member to the tissue.

FIG. 8 shows ablation device 700, as just described, in a position forperforming an ablation procedure on epicardial tissue of heart 140.Device as shown will ablate in a pattern approximating two linesadjacent the right pulmonary veins 142, 144. It should be understood,from the foregoing descriptions of various embodiments, that jaw member704 and ablation members 712, 714 could alternatively be configured inany other suitable shape, size or configuration to ablate in otherpatterns on heart 140. Additionally, device 700 may be moved to avariety of positions to ablate multiple patterns in multiple locationson the epicardial tissue.

With reference now to FIG. 9, a method for ablating cardiac tissue, suchas epicardial tissue, suitably includes contacting cardiac tissue withan ablation device 910, securing the device to the tissue 920 andablating at least a portion of the contacted, secured tissue 930.Various embodiments of the invention will utilize additional steps orsub-steps of these three basic steps, but it should be emphasized thatany additional steps or variations are optional. For example, in someembodiments, contacting the cardiac tissue 910 is preceded by advancingthe device into the patient through a minimally invasive introducerdevice. Contacting the device with the tissue 910 may includepositioning the device using a positioning arm or other positioningdevice. In some embodiments, securing the device to the tissue 920 mayalso comprise invaginating a portion of epicardial tissue partiallywithin one or more suction apertures and/or may include using one ormore suction apertures to dissect through fatty tissue disposed overepicardium. Securing the device 920 may also involve securing withenough force to allow stabilization and/or positioning of the heartitself. And ablation of epicardial tissue 930 may involve ablation inany location or pattern as described above with reference to theinventive devices. Therefore, the descriptions of various methodsprovided herein are offered for exemplary purposes only and should notbe interpreted to limit the scope of the invention as described in theclaims.

Other aspects of a method for ablating epicardial tissue may includeimaging the epicardial tissue and an area surrounding the tissue to beablated, using a visualization device. Such a device may be coupled withthe ablation device or may be a separate imaging device. In someembodiments, an insufflation device may be inserted between theepicardium and the pericardium and insufflation fluid or gas may beintroduced to form a space between the epicardium and pericardium. Thespace may be used to enhance visualization, allow for freer manipulationof devices near the site for ablation and the like. Another aspect mayinclude sensing ablation of epicardial tissue with one or more sensors,as described above. In some embodiments, tissue may optionally be cooledvia a cooling member and/or irrigation of fluid into contact with thetissue. Finally, the actual ablation of epicardial tissue may beaccomplished with any suitable ablation member and form of energy,including RF, thermoelectric, cryogenic, microwave, laser, ultrasound orthe like. In one embodiment, ablation is achieved and/or enhanced bydelivery of one or more drugs to the tissue.

The method may further include the steps of using visual and audiblecues to verify the ablation device is adhered to tissue. For example theuser can hear a suction sound or ‘whistle’ when the suction has beenactivated and the ablation device is not correctly adhered. Also, theuser can hear vacuum pump elevate as vacuum increases. In someembodiments, the user can visually observe the tissue contacting membercollapse when the ablation device is correctly adhered and suction isactivated.

In general, any number of suction pods may be used in the invention, andthe number used may depend on the procedure that is to be performed. Forexample, FIG. 10 shows an embodiment of the ablation device 500including a tissue contact member 534 with only a single elongatedsuction pod 530. In this embodiment, the suction pod 530 extends aselected length of the ablation member 536 and includes graspers 532 tohold the ablation member 536 within the suction pod 530. Any desiredmechanism for holding the ablation member 536 may be used. For example,the graspers 532 may be narrow channel sections in which the ablationmember 536 may be snapped into place, or the graspers 532 may be loopsthrough which the ablation member 536 is slid into place.

In further embodiments, the ablation device may be configured to allowthe ablation member to extend beyond the edge of the tissue contactingmember to allow for ablation to occur outside of the region covered bythe tissue contacting member.

Referring to FIG. 11, an ablation system 800 built in accord with theinvention is shown including an ablation energy source 802 for providingpower to the ablation device 804. The ablation energy source 802 shownis an RF energy source particularly suited for use with ablationapparatus as described herein, but is not limited to such use. Otherkinds of ablation energy sources and ablation devices may be useable inthe invention.

In some embodiments, the ablation system 802 is configured to recognizethe kind of ablation device connected by including keyed plugs. Thus, inthis embodiment, the energy source 802 includes sockets 808 configuredwith specialized shapes to accept only plugs which are manufactured withthe matching shape. The Energy source 802 is configured withpredetermined settings appropriate for the kind of device that isaccepted by that socket shape. More than one socket 808 and associatedpre-determined setting may be included. Ablation devices 804 to be usedwith the energy source will be provided with a plug shape (for exampleplug 806 on ablation device 804) to be received in on of the sockets 808that will provide the appropriate energy requirements.

In another embodiment, the ablation system of the invention includesapparatus for recognizing the kind of device that has been coupled tothe energy source and for automatically adjusting various settings toaccommodate the detected device. Examples include but are not limited toknown logic chip device recognition systems and RFID systems. Thisembodiments can be used in combination with keyed plugs as describedabove.

In another embodiment, the ablation system will provide informationuseful to the treating physician and/or other medical personnel, aboutthe progress of treatment and the status of the equipment. For example,the system may include a feedback loop to self monitor the energydelivery of the system and automatically turn off the delivery of energyonce the treatment is complete. The feedback mechanism may includeelectrical sensors, thermoelectric sensors, microchips, thermistors,thermocouples, Doppler sensors, microwave sensors, and ultrasonicsensors, or thermal energy emitting and receiving devices. In someembodiments, the treatment progress is monitored and indicated with avisual display such as example visual displays 810 and 812. In theseembodiments the sensors may be in communication with processors or othercontrol devices included in the energy source, which can analyze anddisplay the data received from the sensors.

In still further embodiments, the ablation device may include moreelectrodes that are available on the energy source. This allows ablationdevice construction to facilitate longer ablations by utilizing multipleconnections to energy source. For example,

In one embodiment, the ablation device includes a plurality ofelectrodes, and the energy source includes less electrodes than theablation device. In this case, the ablation device preferably includesat least two plugs, with each plug providing power to a subset of theplurality of electrodes on the ablation device. By connecting the firstplug of the ablation device to the energy source, applying ablationenergy to the tissue, unplugging the first plug from the energy source,plugging the second plug of the ablation device in to the energy source,and applying ablation energy to the tissue, all of the ablation elementscan be activated. More specifically, if an energy source includes sevenelectrodes couple to a single plug to power seven ablation segments onthe ablation device, the ablation device may include fourteen separateablation segments. Each set of seven ablation segments would couple to aseparate plug. In use, the first plug is inserted into the energy sourceand the first set of seven ablation segments is activated. Uponcompletion of treatment, possibly without moving the ablation device, asecond region may be ablated by removing the first plug and insertingthe second plug to activate the next seven ablation segments on theablation device. This embodiment can result in a smaller less expensiveenergy source that is still capable of powering a long ablation device.

In one embodiment, a method first includes advancing an ablation devicethrough a minimally invasive introducer device into a patient and to alocation for ablating epicardial tissue. The device is then contactedwith the epicardial tissue and positioned on the tissue with apositioning arm or other device inserted through the same or a separateminimally invasive introducer or incision. Positioning device, in someembodiments, may be a flexible, rigidifying positioner which allows forpositioning and then stabilizing with the same device. The ablationdevice may be placed in any suitable location for ablating epicardialtissue. In one embodiment, for example, ablation device will contacttissue at least partially encircling two pulmonary veins, such as theright superior and right inferior pulmonary veins. The ablation devicemay contact epicardial tissue directly adjacent the bases of the veinsbut may be configured to maintain a safe distance between the ablationmember on the device and the actual veins.

Once the epicardial tissue is contacted, the device may be secured tothe tissue by securing means, such as suction or adhesive. In fact, thedevice may be secured to the tissue sufficiently in some embodiments toallow the heart to be stabilized and/or positioned using the device anda positioner. For example, a beating heart may be stabilized to reduceor eliminate motion during an ablation procedure or may be pulled,turned or otherwise moved into an advantageous position for ablating,visualizing or treating the heart. Suction force may also be supplied insufficient strength to dissect through a layer of adipose tissueoverlying the epicardial tissue, which may provide improved contact ofan ablation member with the epicardial tissue. Once the tissue issecured, at least a portion of the tissue may be ablated by deliveringenergy to an ablation member (or members) on the device. As alreadydescribed in detail, such energy may include any suitable energy and mayadditionally or alternatively include one or more ablative drugs. Afterablation, tissue may be cooled via cooling means and/or ablation oftissue may be sensed with one or more sensors. When an ablativeprocedure is complete, the device may be removed and placed in anotherlocation on the heart for an additional procedure or may be removed fromthe patient altogether.

Another apparatus and method of the invention includes the following.Referring to FIGS. 12 a and 12 b. In some embodiments, the ablationdevice 814 may be deployed using an introducer 816 (best seen in FIG. 12b). The introducer 816 in this embodiment comprises a tube 818 that ispre-bent into a J shape. An obturator 820 with a handle 822 and a shaft828 which is inserted in to the tube 818 with the shaft 828 extendingsubstantially through the length of the tube 818. When the obturator 820is removed, the tube 818 returns to its pre-bent J shape.

A distal end 824 of introducer 816 has a designate region for grasping.A selected instrument may be introduced through a the same or a secondincision to grasp the distal end 824 of the introducer 816 to pull thedistal end 824 of the introducer 816 outside the body of the patient.The distal end 826 of the ablation device 814 of FIG. 12 a is attachedto the proximal end 830 of the introducer 816. The introducer 816 isthen withdrawn until the ablation device 814 is properly positioned.

In the example embodiment of the ablation device 814 seen in FIG. 12 a,the ablation device 814 includes a tissue contacting member 832including a single suction pod 834. An ablation member 836 extendsthrough the length of the tissue contacting member 832 and includesgraspers 838 to hold the ablation member 836 within the suction pod 832.Once the treatment is complete, the ablation device 814 may be decoupledfrom the energy source and pulled out.

An example method for using the invention described above includes thefollowing steps. An introducer is advanced through a first incision intothe transverse sinus cavity with obturator fully inserted. At desiredarea near the pulmonary veins, obturator is withdrawn and the whichallows the introducer to assume its pre-formed J shape reaching roundthe pulmonary veins, possibly also guided by contact with thepericardium. The introducer is preferably long enough to be insertedfrom thoracotomy into transverse sinus cavity around the pulmonary veinsand out through the oblique sinus and out through the same or adifferent thoracotomy. Another instrument is advanced through the sameor different thoracotomy to grasp the distal end of the introducer. Theintroducer is pulled around the pulmonary veins until the distal end isoutside the body of the patient. At this point, both the proximal anddistal ends of the introducer are preferably outside the body of thepatient.

The proximal end of introducer is attached, possibly with luer fitting,to the distal end of an ablation device. Indication markers and lines onintroducer and on the ablation device can be used to assist the user inproperly positioning the ablation device. In a preferred embodiment,circumferential indication markers on the introducer are used as depthmeasurements, and an indication stripe on the surface of the introducerare aligned with similar markings on the ablation device to insure thatthe ablation device will be facing properly when inserted.

In this method, the introducer preferably has torsional rigidity tofacilitate steerability. Further, the introducer is preferably a highlyvisible color for endoscopic visualization and distinguishing fromnatural anatomical colors.

Once the ablation device is in position, suction is applied to adherethe ablation device to the tissue surrounding the pulmonary veins.Ablation energy is applied. Once treatment is complete, the ablationdevice can be removed.

Another method of the invention includes a method of performing a‘hybrid’ medical procedure comprising creating a continuous lesionencircling or partially encircling the pulmonary veins to electricallyisolate the pulmonary veins during a surgical procedure and creatingadditional ablation lesions in the left and/or right atrium, vena cava,endocardium to the mitral valve annulus, or along the left atrialappendage to create a Maze-like lesion set for treatment of atrialfibrillation.

FIG. 13 is an assembly drawing of an ablation device 840 that isconfigured to be used through an introducer or trocar cannula 842. FIG.14 is an exploded view showing the components of the ablation device 840of FIG. 13. A thoracic access port is created between the ribs forinsertion of the ablation device 840. An introducer or trocar cannula842 is placed through the thoracic access port. The ablation device 840includes two elongate flexible polymeric clamp jaws 844, 846. The outersurfaces of the clamp jaws 844, 846 are rounded. The inner surfaces ofthe clamp jaws 844, 846 are flat with an ablation electrode 848, 850 oneach of the clamp jaws 844, 846. Preferably, the ablation electrodes848, 850 are embedded within the flat inner faces near the distal endsof the clamp jaws 844, 846. The ablation electrodes 848, 850 may beconfigured as simple wires embedded in the flat inner faces of the clampjaws 844, 846. Alternatively, each of the ablation electrodes 848, 850may be configured with at least one, and up to about ten, electrodesegments. For flexibility, the electrode segments are preferablyconfigured as helically cut cylinders of metal hypodermic tubing or thelike embedded in the flat inner faces of the clamp jaws 844, 846. Theuse of a flexible or deformable conductive material in the ablationelectrodes 848, 850 provides evenly distributed contact pressure andlesion depth over a variable thickness portion of tissue. Optionally, amesh coating covers the electrode segments to prevent contact of theground and active electrode segments if tissue is not between them. Thecoils are typically dipped in saline before use to insure conductivity.Optionally, the electrode segments may be individually addressable as insome of the embodiments described above. A connection wire 858, 860extends from each of the ablation electrodes 848, 850 to the proximalend of the clamp jaws 844, 846 to allow connection to an ablation powersource. As the clamp jaws 844, 846 are advanced distally though theintroducer or trocar cannula 842, they open up, with the ablationelectrodes 848, 850 on the flat inner faces separating, the faces beingmaintained parallel, and separation distance up to 5 cm. As the clampjaws 844, 846 are retracted proximally through the port, the introduceror trocar cannula 842 exerts forces on the outer faces of the clamp jaws844, 846 causing them to close around the tissue. Preferably, the clampjaws 844, 846 are configured to close around the tissue with theablation electrodes 848, 850 and the flat inner faces in parallelalignment. Alternatively, the clamp jaws 844, 846 can be configured sothat the distal ends close around the tissue first, to prevent thetissue from being squeezed out from between the clamp jaws 844, 846 asthey close. Optionally, one or both of the clamp jaws 844, 846 mayinclude a tooth or other grasping feature near the distal end to preventthe tissue from being squeezed out from between the clamp jaws 844, 846as they close. The length of jaws may be up to 60 cm or more tofacilitate remote insertion.

Optionally, one or both of the clamp jaws 844, 846 could be malleable orinclude a malleable member to allow reconfiguring of the clamp jaws 844,846 for accessing a desired target tissue. The malleable portion mayextend the full length of the clamp jaws 844, 846 or it may be limitedto a proximal, distal or intermediate portion of the clamp jaws 844,846. Alternatively or in addition, one or both of the clamp jaws 844,846 could also have one or more hinge joints or articulating links tofacilitate optimal positioning of the ablation device. For example, aremotely steerable hinge joint may be located on each of the clamp jaws844, 846 just proximal to the ablation electrodes 848, 850 to facilitateaccessing a desired target tissue, while maintaining the ablationelectrodes 848, 850 in an approximately parallel alignment. In alternateconfigurations, the clamp jaws 844, 846 may be joined together, e.g.hinged or molded as one piece in a V-shaped or Y-shaped configuration.Alternatively or in addition, the clamp jaws 844, 846 may be curved tocause the inner surfaces with the ablation electrodes 848, 850 toseparate as the clamp jaws 844, 846 advance distally trough theintroducer or trocar cannula 842. Preferably, the clamp jaws 844, 846will have a central lumen 852, 854 to facilitate a guidewire 856 thatcan be steerable going out of one jaw and into another. This could actto lasso a tissue structure to be brought into the clamp jaws 844, 846.

Preferably, the ablation electrodes 848, 850 on the clamp jaws 844, 846are configured for bipolar ablation. When applying ablation energythrough the ablation electrodes 848, 850, one electrode may act as anactive electrode, while the other acts as a passive ground.Alternatively, the ablation electrodes 848, 850 may both act as activeelectrodes by applying opposite voltages or polarity of alternating(e.g. radio frequency) current to the two ablation electrodes 848, 850.Typically, another ground electrode will be applied to an externalsurface of the patient for safety.

The apparatus can be used to create any lesion, with one jaw endocardialand the other epicardial. In a preferred method, the apparatus is usedwith both jaws positioned epicardially to isolate one or more electricalfocii (pulmonary veins) or peninsula-like tissue structure (such as theleft or right atrial appendage). The apparatus can be used to create oneor more lesions along the atrial base of the pulmonary veins, therebyelectrically isolating the pulmonary veins from the left atrium.

As described above, thermal imaging can be used to visualize the energyemission during an ablation procedure using any of the ablation devicesdescribed herein. In addition, thermal imaging can be used as adevelopment tool for ablation probes. Thermal images of the ablationprocedure in vitro or in vivo allow optimization of the device geometryand energy settings. For example, thermal imaging has been used tooptimize energy settings of ablation devices in an epicardial beatingheart heat sink model. The energy settings thus established weresubsequently used in vivo to achieve the desired depth of heatpenetration in tissue during actual ablation procedures.

While the present invention has been shown and described with referenceto various embodiment thereof, the above and other changes in form anddetail may be made without departing from the spirit and scope of theinvention as defined in the following claims.

What is claimed is:
 1. A method of optimizing parameters of an ablation apparatus including: providing an apparatus for ablating heart tissue comprising: a tubular introducer cannula having an internal lumen; a first elongate jaw and a second elongate jaw, the first and second elongate jaws being sized and configured for insertion through the internal lumen of the introducer cannula in a side-by-side configuration; a first ablation electrode located on an inner surface of the first elongate jaw near a distal end of the first elongate jaw and a second ablation electrode located on an inner surface of the second elongate jaw near a distal end of the second elongate jaw; and a first connection wire extending from the first ablation electrode to a proximal end of the first elongate jaw and a second connection wire extending from the second ablation electrode to a proximal end of the second elongate jaw; wherein the first elongate jaw and the second elongate jaw are configured such that, when inserted through the internal lumen of the tubular introducer cannula in a side-by-side configuration, the first inner surface and second inner surface separate from one another as the distal ends of the first elongate jaw and the second elongate jaw extend beyond a distal end of the tubular introducer cannula, allowing the first ablation electrode and the second ablation electrode to be placed on opposing sides of a portion of heart tissue to be ablated, and, when the first elongate jaw and the second elongate jaw are withdrawn partially into the internal lumen of the tubular introducer cannula, the first inner surface and second inner surface are urged toward one another, pressing the first ablation electrode and the second ablation electrode against the portion of heart tissue to be ablated; performing an ablation procedure on a model of heart tissue; recording a thermal image of the results of the ablation procedure on the model of heart tissue; adjusting parameters of the ablation apparatus based on the thermal image recorded.
 2. The method of claim 1, wherein the first ablation electrode and the second ablation electrode are configured with a plurality of individually addressable electrode segments.
 3. The method of claim 1, wherein the first elongate jaw and the second elongate jaw are configured to urge the first ablation electrode and the second ablation electrode toward one another in parallel alignment.
 4. The method of claim 1, wherein the first elongate jaw and the second elongate jaw are configured such that the distal ends of the first elongate jaw and the second elongate jaw close around the tissue first to prevent the tissue from being squeezed out from between the first ablation electrode and the second ablation electrode.
 5. The method of claim 1, wherein the first elongate jaw and the second elongate jaw each include a malleable portion.
 6. The method of claim 1, further comprising a first guidewire lumen extending from the proximal end to the distal end of the first elongate jaw and a second guidewire lumen extending from the proximal end to the distal end of the second elongate jaw.
 7. The method of claim 6, further comprising a guidewire sized and configured to enter through the first guidewire lumen of the first elongate jaw and exit through the second guidewire lumen of the second elongate jaw.
 8. The method of claim 1, wherein the first ablation electrode and the second ablation electrode are configured with a plurality of electrode segments.
 9. The method of claim 1, wherein the method steps are repeated until the parameters of the ablation apparatus have been satisfactorily optimized.
 10. The method of claim 1, wherein the model of heart tissue comprises an artificial heat sink model of a human heart. 